February 22, 2012

Ants Remember Their Rivals’ Scent

Researchers from the University of Melbourne report they have found that ant colonies share a collective memory for the odor of ants in rival nests.

According to the new research, the ants use the information to identify the rival ants and compete, similar to how sports fans know each other by wearing their teams' colors.

Study leader Professor Mark Elgar from the University's Department of Zoology said the ant colony's collective memory helps give an edge in a competitive world by priming all nest mates with information about rivals before they encounter them.

"This communication highlights the impressive nature of ant societies because the colonies of some species, like weaver ants, can consist of networks of nests containing millions of workers," Elgar said in a press release.

During the study, the team conducted experiments with colonies of weaver ants, which can build nests that can contain up to 500,000 workers.

The scientists took ants from 12 colonies of weaver ants and challenged them with intruders from other colonies that were either familiar, or unfamiliar.

"We find that once an ant has had an encounter with a rival, it can go back to its colony and pass on information about the rival's smell and about how aggressive the interaction was," Elgar said.

The ants defending their colony reacted much more aggressively towards intruders from a nest that a few of the workers had been familiarized with.

They said that this increased aggression persisted between the rival colonies for at least six days after the familiarization trials.

"When a colony was exposed to intruders from the same rival nest repeatedly, we saw the encounters were increasingly aggressive, suggesting that ants were passing on information about the frequency of interaction to their nest mates as well as information about their identity."

The team said its next step will be to try and understand what chemical and behavioral cues the ants use to communicate this information.